EMPLOYEE WAS ON TOP OF A SCREEN DECK REMOVING SIDE RAILS. AS HE WAS HOLDING A BOLT IN PLACE WITH HIS RIGHT HAND TO ALLOW THE FASTNERS (NUTS) TO BE REMOVED, THE AIR GUN WAS BEING APPLIED TO TH E NUTS, THE BOLTS TURNED THROUGH AND CUT HIS RIGHT INDEX FINGER. STITCHES WERE REQUIRED.